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Presenter(s)
Neil Soiffer
Design Science, Inc
NOTE: In order to view this page the way it was intended you must download a browser plugin called MathPlayer. A free download of MathPlayer can be located on the following website. http://dessci.com.
Please click on the following link to view to view the page with the new plugin soiffer.xht
Abstract
Recent progress has made Web-based mathematics more accessible for those with print-disabilities. At last year’s conference, we demonstrated the ease with which mathematical expressions can be added to webpages so that they are accessible [SOI]. This talk reviews past work and presents new work since last year’s conference. The basics of math accessibility remain unchanged: using MathML in your Web documents makes the math more accessible than using images and requires less work on the part of the author.
Putting Math on the Web
To date, most mathematical expressions that are part of webpages are images. Few of these include alt-text and are therefore invisible to blind users and are of limited use to those with low vision. Even for people whose sight is normal, small subscripts or superscripts might be hard to read. Furthermore, images do not scale to meet the size of the surrounding text; may not be aligned with the baseline of the surrounding text; and will generally print poorly. Most applications that generate mathematical images do not provide options for generating the ‘alt’ information during image generation—alt tags must be added later. Furthermore, because there are many ways to aurally render math, what is added to an alt tag might be ambiguous or hard to understand.
In 1998, the World Wide Web consortium (W3C) put forth MathML as its recommendation for putting math on the web. The experience gained from a number of implementations led to version 2 in 2001. At first, browser limitations prevented widespread deployment of MathML. However, by mid-2003, support for MathML was available for many browsers. Current browsers that support MathML include Internet Explorer, Mozilla, Netscape V7, and Firefox. Support for MathML among mathematical applications is commonplace—see www.w3.org/Math/implementations.html for a list of software that supports MathML. A number of publishers have adopted MathML as an accepted format and use it for their internal workflow. MathML has been included as part of other XML-based standards and is expected to become the basis for a math module for DAISY.
Unlike image-based mathematics, MathML accessibility is dependent only upon the rendering software, not upon the authors adding accessibility features. MathML resizes with the surrounding text, so the use of larger fonts in the main document increases the fonts used in the mathematics. Furthermore, there is enough information in MathML so that it can be spoken or translated to braille displays or braille embossers. The effort invested in making a MathML renderer speak math well can be justified because it is used for every equation viewed. Also, having a single audio rendering algorithm means that there is a consistent audio rendering across all documents, rather then different styles of speaking expressions on each page viewed.
MathPlayer
The standard way of viewing MathML in Internet Explorer is to use MathPlayer, a free download from www.dessci.com. Last year, MathPlayer 2.0 was released. This version of MathPlayer makes use of Microsoft’s standard accessibility interface (MSAA) so that it works with a number of screen readers to seamlessly integrate math on web pages into the screen readers. Expressions can also be spoken using a right button menu that is active when the cursor is over an expression. MathPlayer 2.0 added a “MathZoom” feature that magnifies an expression when the expression is clicked on so that small superscripts, etc., can be read more easily.
MathPlayer’s built-in speech rules try to minimize the number of words used to speak the math while producing an unambiguous rendering of the math. For square roots, this means that if the content of a square root is simple, there is no need to delineate where the square root ends so long as we always delineate the end when the content is not a single token. For example consider
MSAA only allows MathPlayer to return a string to the screen reader. This severely limits MathPlayer’s ability to use prosody to speak an expression. MathPlayer’s right button menu item “Speak Expression” speaks the expression directly and does make use of prosody, resulting in more understandable speech. MathPlayer provides an interface for screen readers to take advantage of prosody if they can. Work with various venders towards using that interface is on going.
Numerous studies on math accessibility (e.g., [KAR], [STE]) have shown that for people who are blind, providing only a textual description of the expression is inadequate. Larger expressions require allowing the user to navigate the expression in order to piece together the expression in their mind and to refresh their memory of various parts of the expression. MathPlayer allows users to “browse” expressions using text-based navigations and tree-based navigation. Text-based navigation provides a familiar method for moving around an expression, allowing users to step through or repeat parts of an expression by navigating the words that are spoken. Tree-based navigation allows users to rapidly skip subexpressions they understand and focus on those parts they need to listen to again. For example, navigating the tree view of the expression
using an arrow key results in hearing “x”, “equals”, “fraction”. Moving into the fraction and continuing to explore the expression results in “minus”, “b”, “plus or minus”, and “square root” being spoken. At this point the user can explore the square root or move onto the denominator. We are also experimenting with navigation techniques. We have just begun to work with vendors on incorporating expression navigation into their products.
In addition to speaking mathematical expressions, MathPlayer can also synchronize highlighting of subexpressions as they are spoken. Although there are no studies to indicate that this is useful for people with learning disabilities, it seems very likely highlighting of mathematics will have the same benefits as text highlighting: it focuses readers’ attention on what they are reading along with providing audio reinforcement of what they read. Synchronized highlighting works with TextHELP’s Browsealoud and can also be used from MathPlayer’s right button menu item “Speak Expression”. We are working with other vendors so that they can make use of this feature of MathPlayer.
Although MathPlayer represents a large improvement over using alt text on images in terms of being accessible, more work needs to be done so that all of the needs of users with print-disabilities are meet. Many blind people are more comfortable using braille displays or embossed output using a linear math braille code such as Nemeth code or a two-dimensional representation such as DotsPlus [GAR] to understand larger expressions. Support for DotsPlus is relatively easy to add and we hope to partner with existing projects working on translation to math codes so that feature can be added to MathPlayer in a timely manner. Plans for other features include support for various verbosity levels and customizable speech strings and speech rules so that MathPlayer can be localized to different languages or methods of speaking expressions.
Summary
In the past, math in Web pages was not accessible to those with print-disabilities. With the advent of wide support for MathML in browsers, this should no longer be the case as demonstrated by the accessibility features of Internet Explorer+MathPlayer:
• matching the font size of the expression with the (large) font size of the document
• providing a method to magnify one or more expressions
• speech output and integration with screen readers
• keyboard navigation of larger expressions
• synchronized highlighting of speech
Accessibility using MathML requires virtually no effort on the part of the author since most math applications support easy generation of MathML. For example, using Word+MathType (the professional version of the equation editor that is a part of Word) a single button click will save the word document out appropriately. Word+MathType can even be used to increase the accessibility of existing Word documents that contain math by saving those documents as Web documents and reading them in IE+MathPlayer.
Work on MathPlayer was supported in part by a SBIR grant from the National Science Foundation.
References
[GAR] Gardner, J., (2000). Future Braille Codes and Fonts in Braille into the Next Millennium, ISBN 0-8444-1021-7, edited by Dixon, J. 514-531.
[KAP] Gaylen Kapperman, Jodi Sticken. Mathematics instruction for visually disabled students using assistive technology, CSUN conference 2003 (www.csun.edu/cod/conf/2003/proceedings/282.htm).
[KAR] Karshmer, A. , Gupta, G. , Geiiger, S. , Weaver, C., Reading and writing mathematics: the MAVIS project, Proceedings of the third international ACM conference on Assistive technologies, p.136-143, April 15-17, 1998, Marina del Rey, California
[SOI] Soiffer, N., ACCESSIBLE MATHEMATICS MADE EASY, CSUN conference 2004 (www.csun.edu/cod/conf/2004/proceedings/177.htm).
[STE] Stevens, R.D., Edwards, A.D.N, and Harling, P.A. Access to mathematics for visually disabled students through multimodal interaction. Human-Computer Interaction, 12, (1997) 47-92.
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